The present invention relates to a seat device for a vehicle which comprises a main seat having a main-seat cushion and a main-seat back, and a sub seat having a sub-seat cushion and a sub-seat back, wherein the sub-seat back is supported at the main-seat back via a sub-seat back support member so as to be foldable at the main-seat back.
Conventionally, a seat device for a vehicle which comprises a second-row rear seat having a pair of main seats and a sub seat provided between them is known. Herein, this seat device may provide various seat arrangements, such as a two-passenger mode in which two passengers can be seated serenely in a wide seat space formed by the main seats and the sub seat, a three-passenger mode in which three passengers can be seated in the main seats and the sub seat, a walk-through mode in which the sub seat is stored at either one of the main seats so that a walk-in space can be formed between the second-row seat and a third-row seat, or some use mode in which the sub-seat cushion is used as a container, or the sub-seat back is used as a cup holder.
Meanwhile, in general, the above-described sub seat (assist seat) may be necessary to be made with a light weight because it is foldable at the main seat, and it may not have enough strength to attach a seatbelt for the sub seat. Accordingly, a two-point type of seatbelt for the sub seat is practically provided at the main seat beside the sub seat to restrain the passenger seated in the sub seat. However, it is preferable that a three-point type of seatbelt be provided for the sub seat, and in this case it may be considered that a shoulder anchor to guide the seatbelt for the sub seat is provided on the side of the seat back of the main seat. Herein, since an appearance of the seatbelt in its non-use state may deteriorate and the seat back of the sub seat may be configured not to interference with this shoulder anchor, there was a problem in that any sufficient width-direction space of the seat back of the sub seat could not be ensured.
Japanese Patent Laid-Open Publication No. 2004-249782 discloses the seat device for a vehicle comprising the main seat and the sub seat, in which the seat back of the sub seat is attached to the seat back of the main seat via the horizontal axis so as to rotate in the vehicle longitudinal direction. Further, the seat back of the sub seat is attached to the seat back of the main seat via the vertical axis so as to be folded. Moreover, the seat cushion of the sub seat can provide either its sitting state or its storage state. This publication, however, discloses nothing about a seatbelt device for a sub seat which comprises a webbing, retractor and so on.
Japanese Patent Laid-Open Publication No. 11-129800 discloses the three-point type of seatbelt applied to the sub seat. Herein, while the seat cushion of the sub seat is supported at the seat cushion of the main seat, the seat back of the sub seat is attached to the seat cushion of the sub seat. Accordingly, there was a problem in that the rigidity of the sub seat may be insufficient, so that the sitting feeling would deteriorate. Further, since the shoulder anchor of the seatbelt for the sub seat is attached to the seat back of the main seat, there was the same problem described above.